1. Field of the Invention
This invention is concerned with devices and methods for harvesting cells. More particularly one embodiment of this invention relates to a device and a method for enabling the direct dispersion of cells from tissue for medical or research use.
2. Related Art
Advances in medical science and medical therapies have spurred the need for methods and apparatuses for isolating and collecting living cells for later use in medical or research procedures. Such procedures include seeding of the isolated cells to enhance grafting of tissue such as with burn victims and insertion of cells as a specific cell therapy to assist or augment the functioning of the recipient""s own diseased or injured tissue or organs such as the liver.
Among the numerous methods and devices disclosed for isolating living cells are those disclosed in EP Pat. No. 446 450 B1. This patent discloses a device for digesting and processing tissue to produce endothelial cell products. One embodiment disclosed consists of a system of five primary subsystems: 1) fat collection unit (see FIG. 1); 2) digestion unit (see FIG. 2); 3) endothelial cell isolation unit (see FIG. 3); 4) vascular graft processing unit (see FIG. 4); and 5) endothelial cell deposition unit (see FIG. 4). An alternate embodiment (see FIG. 14) is disclosed consisting of a single vessel consisting of a vessel with three chambers: a digestion chamber (210), a waste chamber (212), and an isolation chamber (214). The digestion chamber (210) is separated from the waste chamber (212) by a plate (218) containing a normally closed check valve (220). A vent tube (222), containing a floating ball check valve (224), extends from the waste chamber (212) into the isolation chamber (214). The digestion chamber (210) communicates with the outside by means of a series of ports (228, 229, 230). The digestion chamber (210) is separated from the isolation chamber (214) by a screen (232). The isolation chamber (214) possesses two ports (234 and 236), each of which contains a two position valve (238 and 240). The first position allows communication between the middle of the ampoule (235) and the upper and lower portions of the ampoule. The second position allows communication between the middle of the ampoule (235) and the outside ports (234 and 236). Initially, both ampoule valves (238 and 240) are in the first position. The device is used as a catch-trap in line with a liposuction vacuum line connected to ports (228 and 230). After fat is collected, the liposuction lines are disconnected, ports 228 and 230 are capped and rinse solution (Media 199E, Hanks, saline, PBS, or other physiological buffered solution) is introduced through port (229). The fat is agitated in the rinse solution by any external means such as shaking. The device is then placed in a centrifuge, ampoule side up, and spun until the normally closed check valve (220) opens and the rinse solution drains into the waste chamber (212). The ball valve (224) in the vent tube (222) opens during this centrifugation step allowing the waste chamber (212) to vent air which is displaced by rinse solution. Digestion enzyme solution (collagenase, dispase, trypsin, or other tissue dissociation enzyme) is then introduced through port (229), again followed by agitation. When digestion is complete, the device is again centrifuged, ampoule side down. In order to isolate the endothelial cells which have separated into the ampoule (235), both valves (238 and 240) are turned to their second positions. The cell xe2x80x9cpelletxe2x80x9d may then be flushed out by attaching a pressure line to one of the ampoule ports (234 or 236).
U.S. Pat. No. 5,409,833 also discloses a single device for use in receiving, cleansing, digesting and isolating certain identifiable cells from tissues wherein the device comprises a housing defining a process chamber which includes a lower conical portion and a screen basket including a conical portion defining a lower part of the screen basket. The screen basket and its conical portion is positioned within the process chamber where the basket""s lower conical portion defines a gap separating the screen basket from the housing with the size of the gap being substantially consistent across the screen basket and its conical portion. In use, the device requires several rinsing stages, a cell digestion stage, involving use of valving to produce, after centrifugation, a cell xe2x80x9cpelletxe2x80x9d of microvessel cells. This pellet is required to be removed introducing of a sterile buffered liquid through a port upstream of the xe2x80x9cpelletxe2x80x9d which forces the xe2x80x9cpelletxe2x80x9d through a second port which exits the device. The ports are required to be opened and closed by valves. Due to the intricacies of the device, it would be expected that reuse of the device in subsequent procedures would require thorough sterilization which could become hampered due to the intricacies of the passages and valving in the device.
While the foregoing patents disclose embodiments of cell separation devices as single apparatuses, it appears that operation may be cumbersome with the operator having to be intimately familiar with all the functions of the ports and valving for the various connections thereto. Additionally, reuse of these devices would appear to require thorough sterilization and cleaning procedures due to the complexity of the devices"" passageways to insure sterile reuse of the devices.
The present invention provides an advance over the prior art by providing a sterile device and method of isolating cells from tissue in a simplified and rapid procedure as hereinafter described. The device also does not require any valving which makes cleaning and sterilization for reuse simpler as the intricacies of the passages of the previously disclosed devices are not present. Alternately, the device of the present invention is ideally suited for disposal use, thereby eliminating the concern of cleaning and sterilization of used devices.